Background

Infection after Unicompartmental Knee Arthroplasty (UKA) is an uncommon but severe complication, not well studied, with a lower incidence compared to a Total Knee Arthroplasty (TKA). Little data is available regarding the modern treatment of Periprosthetic Joint Infection (PJI) after UKA. The purpose of this article is to present the results of the largest multicenter clinical study of UKA PJI treated with DAIR.

Methods

In this retrospective study, clinical data was collated between January 2016 and December 2019. Twenty patients had early infections, 19 of whom were submitted to Debridment, Irrigation, polyethylene liner exchange with Implant Retention (DAIR) and intravenous antibiotic therapy followed by oral treatment.

Results

DAIR procedure showed an overall survivorship free from septic reoperation of 84.2% . The overall survivorship free from all-cause reoperation was 78.9%. The usage of DAIR procedure had a higher than expected success against earlier published data for UKA and significantly better than the same procedure in TKR.
Analysis of UKA infected cases reveals the most common bacteria are coagulase-negative Staphylococcus, Staphylococcus aureus, and group B Streptococcus. Three patients underwent a second DAIR procedure successfully: one of these patients had a TKA for medial osteoarthtritis and one was lost at follow up (FU). All other cases had no recurrence at last FU.

Conclusion

Following UKA a significantly higher proportion of the knee joint remains of native tissue. This may alter the response to the rare challenge of infection. Surgeons might wish to adopt a slightly different strategy than in TKA infection, with more emphasis on the less invasive and potentially more successful DAIR procedure.